Time Sharing System in OS

Overview

Time-sharing system is a type of operating system which allows multiple users to access resources of a particular system from different locations. These systems were introduced in the 1960s as one of the perceptible models and represented a major part of the technological shift.

The architecture of a time-sharing system is also known as multi-tasking system which is a logical extension of the concept of multiprogramming. In this method, the time of a single processor is shared among different users over a network simultaneously.

Time-sharing system performs multiple tasks over a single Central Processing Unit (CPU). The processor switches between the different assigned tasks to complete them individually. This switch occurs so frequently that the overall throughput remains unaffected from this approach. For instance, the processor executes each of the user programs in a short burst during the transaction process. This short burst is also referred to as a single quantum of computing. This means, when ‘n’ users want to use the processor, then each one of them can get a dedicated time quantum to complete their tasks.

The time-sharing operating system uses CPU scheduling as well as multiprogramming concepts to offer each of the users a small part of the operating time. The concepts of the time-sharing operating system align with those of the batch processing systems. It is also said that computers which were designed primarily as batch systems have been changed to operate as time-sharing systems.

Basic features

·         Every user gets a dedicated time for the operation.

·         Simultaneous tasks are carried out at once.

·         Tasks no longer have to wait for the previous task to finish to get the processor.

·         Quick processing of multiple tasks.

·         Equal time given to all the processes so that they operate smoothly without any significant delay. 

The following figure states the basic structure of a time-sharing system.

Learn more about types of operating system here.

Reasons to use time-sharing operating system

• To run multiple tasks simultaneously.
• More efficient and convenient to use.
• Better performance

Advantages

Some of the advantages of the time-sharing system are as follows:

• Quick response to the users.
• No duplication of data.
• No duplication of software applications.
• Reduces CPU idle time.

Disadvantages

Some of the disadvantages of a time-sharing system are as follows:

• Problem of reliability
• Risk regarding security and reliability of user programs and data.
• Data communication conflicts.

Examples

Several computers were developed as time-sharing operating systems. These included some concepts of batch processing systems as well. Some of these are:

• Multics
• Unix
• TOPS-10 (DEC)
• TOPS-20 (DEC)